Hmmm I don't think two wrongs make a right, do you? Regardless of what he did or didn't do for you on Mothers' Day, I think you should be the 'better' person and if you think he's a wonderful father, then celebrate that with him on the day.
I don't expect anything on Mother's Day, but if I do get something, it's a bonus :D Our children are already our gifts. ;)
I'm going to do something up for DH for Father's Day because I think he's a wonderful father to our girls and deserves it.
I'm sure you're a great mum, you don't need a gift from anyone to prove that!